The Sérsic-Pastoriza galaxy NGC 1808 - 1 . Radio-continuum, optical and H I observations

Abstract

Summary We present radio-continuum observations made at high angular resolution with the VIA at 20, 6 and 2 cm of the central region of the Sersic-Pastoriza galaxy NGC 1808. These observations reveal a population of compact radio sources, reminiscent of those found in the archetypal starburst galaxies M82 and NGC 253. The bulk of these compact features are not coincident with the optical hot-spots and are likely to be individual or unresolved groups of SNRs. We have also made H i observations of NGC 1808 with the VLA (very large array). Although this was primarily to search for unusual motions which may enable us to understand the nuclear activity, we also obtained information on the large-scale distribution and dynamics of gas in this system. The neutral hydrogen is largely concentrated in a central bar, with weak emission from the spiral arms. An absorption profile against the radio emission from the nuclear region shows two features straddling the systemic velocity. The velocity field of the galaxy is largely consistent with rotation although there is evidence of significant non-circular motions in the bar. We discuss any possible relationship between these non-circular motions and the starburst/nuclear activity in the central region of NGC 1808.